There's an alternate form of the third person plural perfect active indicative. Instead of, say, habuerunt, a poet might write habuere, to make the word fit with the meter, but that looks like the infinitive! How can I tell them apart?


3 Answers 3


Three considerations are helpful to distinguish between the infinitive and the alternative 3rd person plural perfect ending:

  1. -ēre is added to the perfect (3rd) stem, while the present infinitive is formed on the present (1st) stem. Although the perfect infinitive is also formed on the 3rd stem, its form (isse) is easily distinguishable.
  2. -ēre has a long ē vowel. Besides the second conjugation (e.g. vidēre), all other (common) verbs are formed with an -a (1st conjugation, e.g. laudare), a short -e (3rd conjugation -o and -io, e.g. mittere and capere), or an -i (4th conjugation, e.g. audire).
  3. Context! I cannot think of (though there probably are examples of...) a grammatical Latin sentence where an infinitive or a 3rd person perfect verb could be swapped without doing violence to the syntax.

There are cases where (1) and (2) will fail, as in the case of vidēre which happens to have the same vowel length and the same 1st and 3rd stem. In this case, context is key: Regressi eum vidēre only makes sense where vidēre is perfect. Te vidēre volo only makes sense as an infinitive.

Regarding your footnote, yes, this contraction only normally exists in the active indicative. The perfect subjunctive (e.g. viderint) has no contraction and the perfect passive (both indicative and subjunctive) are compounds formed with the fourth principle part (visi sunt, sint).

  • 1
    I'd like to quibble at (sic) your second point: In plenty of writing, the macron isn't provided over the e.
    – anon
    Mar 10, 2016 at 18:00
  • 1
    The rule at work here is the length of the vowel, which is there regardless of whether a macron makes it explicit or not. Granted though that this only helps if you hear the words (well) pronounced or happen to know the length.
    – brianpck
    Mar 10, 2016 at 18:38
  • 1
    That's what I mean. I imagine most people are reading Latin, and many sources don't have macrons. It's still worth mentioning, of course; I just wanted to point out the obvious pitfall of that -- i.e. that no macron doesn't mean it's an infinitive.
    – anon
    Mar 10, 2016 at 19:18
  • 2
    @QPaysTaxes, if it's verse, you know can often tell the length of the vowel by the metre. In prose you can't, so you'll have to rely on something else.
    – Joonas Ilmavirta
    Mar 10, 2016 at 19:21

It is very rarely the case that the alternative form of the perfect in third person plural really looks like present infinitive. If you know how to conjugate your verbs, there is rarely a problem.

In the second conjugation this happens with the following words (I have only listed the relevant forms):

  • moveō, mōvī (with possible prefixes)
  • sedeō, sēdī (one-syllable prefixes weaken the present stem but not the perfect stem, so ambiguity is lost: assideō, assēdi but circumsedeō, circumsēdī)
  • attondeō, attondī (reduplication in the absence of prefixes: tondeō, totondiī)
  • caveō, cāvī
  • faveō, fāvī
  • foveō, fōvī
  • videō, vīdī (with possible prefixes)
  • respondeō, respondī (reduplication without prefixes: spondeō, spopondī)
  • strīdeō, strīdī

The only ones of these that have the same vowel lengths and are thus metrically indistinguishable in verse, are attondere, respondere and stridere.

In the third conjugation the infinitive always has a short -e- before the ending -re, so vowel length can always tell them apart. In the absence of macrons there are more look-alikes in third conjugation than in the second one, so I will not list them here. (I might do so later.)

If I missed some verbs, let me know. I'm travelling now and I don't have access to my printed dictionary that I would love to use here.

  • That's why I said looks like, not is identical to. They look similar.
    – anon
    Mar 10, 2016 at 19:59

There are two main ways. The first is context; if there's no other main verb, by process of elimination, the word in question has to be. This is typically how I figure it out; I'll read the sentence taking it as an infinitive, realize there's no main verb, and go back to look at all of the candidates.

The second is that this specific kind is an abbreviation, so it uses the same stem as the full form -- namely, the perfect. Notice the difference between habeo, habere's infinitive and this form:

  • Habere
  • Habuere

One rule of thumb to tell if it's the perfect stem instead of present is that present stems rarely end in -u, -v, or -x, while perfect stems often do. However, there are many exceptions to this rule -- for example, the present stems of abluere, induere, salvere, exere, and mixere, and the perfect stems of such as bibi, feci, egi, arsi, cecini.1

1: Source: C.M.Weiner

  • 1
    Off the top of my head, those with u, v, or x in the present stem include abluere, induere, salvere, exere, and mixere, while many perfect stems do not include those, such as bibi, feci, egi, arsi, cecini.
    – cmw
    Mar 10, 2016 at 17:53
  • 1
    @C.M.Weimer Changed it to "rule of thumb", and added a note about how the only real way to tell is to know the word or have a dictionary.
    – anon
    Mar 10, 2016 at 17:57

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.